Method and system for measuring patterned structures

Abstract

A method and system are presented for determining a line profile in a patterned structure, aimed at controlling a process of manufacture of the structure. The patterned structure comprises a plurality of different layers, the pattern in the structure being formed by patterned regions and un-patterned regions. At least first and second measurements are carried out, each utilizing illumination of the structure with a broad wavelengths band of incident light directed on the structure at a certain angle of incidence, detection of spectral characteristics of light returned from the structure, and generation of measured data representative thereof. The measured data obtained with the first measurement is analyzed, and at least one parameter of the structure is thereby determined. Then, this determined parameter is utilized, while analyzing the measured data obtained with the second measurements enabling the determination of the profile of the structure.

1. A method of generating a library of simulated diffraction signals of a patterned structure, said method comprising:
 obtaining at least one simulated profile by simulation of a manufacturing process of a patterned structure; 
 associating hypothetical process parameters with a simulated profile; 
 varying the hypothetical process parameters within a range to generate a set of hypothetical profiles; 
 adjusting the range to vary the hypothetical parameters based on the process simulation;
 determining the required hypothetical process parameters to associate with the hypothetical profile based on the process simulation; and 
 
 generating a set of simulated signals from the set of hypothetical profiles based on an optical model. 
 
     
     
       2. The method of  claim 1  comprising:
 determining a resolution for the set of simulated signals; and 
 varying the hypothetical process parameters used in generating the simulated signals at an increment corresponding to the determined resolution. 
 
     
     
       3. The method of  claim 1 , wherein said set of simulated signals is generated using the adjusted range to vary the hypothetical parameters. 
     
     
       4. The method of  claim 1  comprising:
 generating a library by pairing each simulated signal in the set of simulated signals with each hypothetical profile in the set of hypothetical profiles; and storing said pairings of simulated signals and hypothetical profiles. 
 
     
     
       5. The method of  claim 1 , wherein said manufacturing process includes etching. 
     
     
       6. The method of  claim 1 , wherein said manufacturing process includes photolithography. 
     
     
       7. The method of  claim 6 , wherein said process parameters include focus conditions. 
     
     
       8. The method of  claim 1 , wherein said diffraction signal comprises spectral data. 
     
     
       9. The method of  claim 8 , wherein said spectral data comprises polarized spectrum. 
     
     
       10. The method of  claim 1  wherein said diffraction signal comprises angular distribution of light intensities. 
     
     
       11. The method of  claim 1 , further comprising defining at least one of the following: type of the manufacturing process, type of the model, type and range of input parameters of the optical model. 
     
     
       12. The method of  claim 1 , further comprising providing data characterizing an initial parameter of the patterned structure prior to being processed by said manufacturing process. 
     
     
       13. The method of  claim 12 , wherein said data characterizing said patterned structure comprises at least one of the following: resist thickness, optical coefficients, absorption coefficient, sub-layer reflection. 
     
     
       14. The method of  claim 1 , wherein said generating the set of simulated signals is based on a Rigorous Couple Wave Analysis method. 
     
     
       15. The method of  claim 1 , wherein said generating the set of simulated signals is based on a modal method. 
     
     
       16. The method of  claim 1 , wherein said generating the set of simulated signals is based on a hybrid method. 
     
     
       17. The method of  claim 1 , wherein said patterned structure comprises a photoresist formed by a photolithography. 
     
     
       18. The method of  claim 1 , wherein said patterned structure is characterized by two-dimensional periodicity. 
     
     
       19. The method of  claim 1  wherein said patterned structure includes via-holes.